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S. Elderkin, J. De la Cruz, J. P. Garcia, Jr., D. C. Ritterband; Angle Structures in Patients Implanted With Type I Boston Keratoprosthesis Utilizing Anterior Segment Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3269.
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© ARVO (1962-2015); The Authors (2016-present)
To present an alternative technique for evaluation of anterior segment angles and their interaction with the back plate in vivo, in eyes implanted with the Boston type I Keratoprosthesis (K-Pro).
13 eyes implanted with a Boston Type I keratoprosthesis were studied by the non-contact technique of AS-OCT (AC Cornea OCT prototype, OTI, Canada). Cross sectional horizontal images were obtained and angle structures were recorded temporally and nasally as well as the distance from the most peripheral end of the back plate to the angle. 12 of the 13 eyes were implanted with the 8.5mm back plate KPro, and one with the 7.0 mm plate. 6 eyes are aphakic, and 7 eyes had pseudophakic implants.
All eyes had multiple procedures prior to KPro placement including PKPs, and glaucoma device insertions. Of the 13 eyes, 6 had angles that were closed both nasally and temporally. 5 out of 6 of these closed were in eyes with implanted pseudophakic IOLs. Of the remaining eyes, the average measurement of the angles was 37 degrees with a range of 6.1 to 50.1 degrees. Of the 13 eyes, 12 were 8.5mm back plates. In 2 of these, the back plate to angle distance was not seen, and therefor could not be measured. The remaining 10 had an average distance of 2.25 mm with a range of 1.2 to 3.6mm. The 7.0 mm back plate KPro was one of the eyes with a closed angle. However, it has a nasal back plate-to-angle distance of 2.5mm and temporal distance of 3.6mm. 8 of the 13 eyes had Baerveldt filters placed pars plana. 4 of these had closed angles.
Anterior segment optical coherence tomography (AS-OCT), can serve as a high resolution alternative technique for evaluation of anterior segment angles and their interaction with the back plate, in eyes implanted with the Boston type I Keratoprosthesis (K-Pro). Evaluation of the anterior segment angles in these eyes provides valuable information and allows for improved assessment of patients that are at higher risk of development of glaucoma or the progression of synechiae formation or occlusion of angles due to anterior segment crowding. Each of these eyes has great variability with respect to angle degrees and distance between the angle and back plate. With the use of AS-OCT, we can now image with improved accuracy and obtain a better post-operative angle evaluation in these KPros that cannot be seen using conventional techniques like gonioscopy. In addition, further studies could use this information to evaulate more of these smaller-sized back plates and their relationship to the angle to assist with the design of the keratoprostheses.
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